FIG. 32 shows one example of an LED module. The LED module 900 shown in FIG. 32 has a structure in which three LED chips 931, 932 and 933 are mounted on an elongated rectangular substrate 910. A plurality of electrodes 921, 922, 923 and 924 are formed in the substrate 910. The LED chips 931, 932 and 933 are wire-bonded to the electrodes 921, 922 and 923, respectively. The electrode 924 is a so-called common electrode and is electrically connected to the LED chips 931, 932 and 933 through a wire. The three LED chips 931, 932 and 933 are surrounded by a case 950. The case 950 has a substantially frame-like shape and is made of an opaque resin. The internal space of the case 950 is filled with a transparent resin (not shown). The LED module 900 is often referred to as a side view type LED module, which is mounted to a mounting substrate or the like by using a lower surface (shown in FIG. 32) extending in the longitudinal direction of the substrate 910 as a mounting surface. The LED chips 931, 932 and 933 are configured to emit red light, green light and blue light, respectively. These three types of light emitted from the LED chips 931, 932 and 933 are mixed with one another so that the LED module 900 can emit white light.
However, in recent years, there is an ever increasing demand for reduction in the size of the LED module 900. For example, the width of the substrate 910 needs to be made smaller in order to reduce the projection height of the substrate 910 from the mounting substrate to which the LED module 900 is mounted. As a consequence, a space for accommodating the LED chips 931, 932 and 933 becomes narrower. The space for accommodating the LED chips 931, 932 and 933 includes not only an installation space of the LED chips 931, 932 and 933 per se but also a space for arrangement of the wires bonded to the LED chips 931, 932 and 933 and for arrangement of the portion of the common electrode 924 to which the wires are connected. Thus, the area allocated for the electrodes 922 and 923 in the substrate 910 is not considered insignificant at all. It is therefore not easy to reduce the width of the substrate 910.
Alternatives to the side view type LED module as described above may include a top view type LED module, for which there is also a demand for reduction in the size of the top view type LED module.